Various types of machines for tape sealing shipping cartons are known. Generally, such machines apply and press separate runs of sealing tape (most commonly a pressure-sensitive type) longitudinally from the carton front end, along the top and/or bottom side, and then onto the carton rear end. A machine which seals cartons at both top and bottom sides thereof and with tape applicator means disposed at the top and bottom sides of the carton travel path is, e.g., described in commonly owned U.S. Pat. Nos. 4,028,865 and 4,041,675. Such machines are suitable for tape sealing rectangular cartons of a wide range of carton heights, since the top tape applicator means is mounted on a vertically adjustable head beam to accommodate positioning same in correspondence to a given carton height. These machines are not, however, suited for tape sealing shallow depth cartons since tape securement at the front and rear ends of short height (e.g., 1/2" to 21/4" high) cartons, if at all possible, would be poor and the carton easily could become opened during handling subsequent to taping.
Cartons in which the foregoing problem can be encountered are one-piece folders and mailers, e.g., book-mailer boxes or cartons, slotted document envelopes, etc. These cartons have very short heights as noted above so that tape sealing of such a shallow depth carton, and which insures proper anchorage of the initial and terminal lengths of the tape run, desirably follows a course in a wraparound at both the front and rear of the carton and along the top since these types of cartons are formed from a one piece blank and therefore have fold down abutting flaps which require sealing only on the top. Machines which can tape shallow depth cartons are disclosed in U.S. Pat. Nos. 2,083,257 and 4,052,240 but these patented machines have drawbacks. For example, the machine of U.S. Pat. No. 2,083,257 is of very complicated construction and uses a cumbersome elevating and retracting brush carrier to wipe initial and terminal tape lengths to the underside of the mailer. The machine of the U.S. Pat. No. 4,052,240 requires that carton travel through the machine be stopped to tape the terminal tape length around the corner formed by the rear wall and bottom.
A more significant shortcoming of the machines of the U.S. Pat. Nos. 2,083,257 and 4,052,240 patents is that such machines cannot readily be used for taping cartons of random heights and over a wide range of carton heights. Mailer type cartons (shallow depth) will be taped in a continuous tape run wrapping around from top to bottom at the carton ends and along the carton length at the top as illustrated in the two patents aforesaid. Taller height cartons (above 21/4" and up to heights of 20" or more) on the other hand have infolded flaps at both the top and bottom which require taping and hence, are taped with separate courses at the top and bottom and in tape runs that respectively run down and up the front and rear ends of the carton. Thus, and as illustrated in the disclosures of U.S. Pat. Nos. 4,028,865 and 4,041,675, there is a full sealing span of longitudinally directed tape at the bottom of the carton which is especially important to insure against carton flap opening at the bottom under the imposed load of the carton contents after the carton is sealed and then shipped by the user to its intended end destination. While the machines of the U.S. Pat. Nos. 2,083,257 and 4,052,240 patents may have a certain adjustability regarding taping cartons of different heights, that adjustability and hence the sizes of cartons which can be taped therewith is limited. In any event that taping function with these machines is the same for all carton heights, i.e., the taping course is the same and there is no continuous length of tape applied at the carton bottom. Thus the machines disclosed in all of the patents mentioned above, lack capacity or adaptability for use in tape sealing shallow depth cartons with a single wraparound tape run on the one hand, and on the other hand taller height cartons with two separate continuous tape runs one at the carton top and the other at the carton bottom, which different taping courses represent the most optimized taping for the different sizes of the cartons involved.